In general, battery modules are formed in a structure in which a plurality of cells are assembled by series and/or parallel connection. Such a battery module is illustrated, which typically includes: a cell assembly in which a plurality of cells are arranged and stacked in one direction; and a frame having a plate capable of surrounding the cell assembly.
A battery module of the related art is manufactured in a structure in which a cell assembly 20 is surrounded by a frame 10 formed by an extrusion or die casting method as shown in FIG. 1.
However, such an extrusion or die casting method is a major cause of increasing the unit price of battery modules due to high process costs, and since the expansion of battery modules is forcibly inhibited, the lifespan of cells may be negatively affected.
Alternatively, Korean Patent Application Publication No. 2014-0118734 discloses a battery module including a housing having a side plate, a bottom plate, and a bent portion between the side plate and the bottom plate, and the bent portion is formed such that the side plate and the bottom plate are biased in a direction toward a battery cell.
Korean Patent Application Publication No. 2015-0142790 discloses a battery module in which an upper strap is further included unlike an end plate of the related art so as to prevent a change in the external shape of the battery module caused by a swelling phenomenon.
Although techniques as described above have been proposed, there is a limit to decreasing the weight of battery modules of the related art, and since there is no technical means for stably supporting battery modules and reducing material or process costs while sufficiently allowing the expansion of an end plate caused by swelling, measures are needed.